In this con­text, it should also be of in­ter­est that the fre­quency and phase co-or­di­na­tion of the heart rhythms of mother and child in the womb also par­tici­pate in this noc­tur­nal in­ten­si­fi­ca­tion of the rhyth­mic func­tional or­ders. Thus, it could be proven that, while preg­nant women were asleep at night, not only is the heart rate ratio of mother and child more strictly ad­justed to the whole num­bered value of 1:2, but that, at the same time, a phase co-or­di­na­tion sets in dur­ing which the child’s heart beat pre­fers cer­tain phases of its mother’s heart beat. (il­lus­tra­tion 15). At the same time, this ex­ample makes the func­tional im­por­tance of har­monic co-or­di­na­tion be­tween rhyth­mic func­tions clear, as with cor­rect phase co-or­di­na­tion, an un­eco­nom­ical-si­mul­ta­ne­ous ar­ri­val of the mother’s and child’s pulse waves in the pla­centa can be avoided.